The Olive

The Olive (Olea europaea) is a species of small tree in the family Oleaceae, native to the coastal areas of the eastern Mediterranean region, from Lebanon, Syria and the maritime parts of Asia Minor and northern Iran at the south end of the Caspian Sea. Its fruit, the olive, is of major agricultural importance in the Mediterranean region as the source of olive oil.

The Olive tree is an evergreen tree or shrub native to the Mediterranean, Asia and parts of Africa. It is short and squat, and rarely exceeds 8–15 meters in height. The silvery green leaves are oblong in shape, measuring 4–10 cm long and 1–3 cm wide. The trunk is typically gnarled and twisted.

The small white flowers, with four-cleft calyx and corolla, two stamens and bifid stigma, are borne generally on the last year's wood, in racemes springing from the axils of the leaves.

The fruit is a small drupe 1–2.5 cm long, thinner-fleshed and smaller in wild plants than in orchard cultivars. Olives are harvested at the green stage or left to ripen to a rich purple colour (black olive). Canned black olives may contain chemicals that turn them black artificially.

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Mad TV - Olive Garden Commercial

Olive Oil Extraction - Part 5

Alternative configurations
Some producers, in order to maximise product quality, choose to combine the traditional grinding method, the stone mill, with a modern decanter. This technique produces more selective grinding of the olives, reduces the malaxation time olive paste, and avoids the complicated cleaning of the olive press fibre disks. Because the use of the stone mill requires a loading and unloading phase, this extraction method is discontinuous, i.e. there times where the all machinery is stopped, therefore it is generally not used on a large commercial scale, being applied only at small scale olive mills producing high quality olive oil.

Consumer point of view
High quality olive oil can be obtained by all the methods if proper measures are taken. Olive oil quality is equally dependent on the quality of the olives themselves and on the time they have to wait from harvesting to extraction, in addition to the extraction method itself.

The 2 worst “enemies” of olive oil are: Oxygen and light. Once an olive is harvested, it should be pressed within 24 hours. Oxidation begins immediately upon harvesting. In the period between harvest and grinding, the fruits' enzymes are very active and increasingly degrade the endogenous oil, and therefore oil obtained after a longer wait is of lower quality, presenting higher acidity (oleic acid percentage).

In addition, if additional oxygen is allowed to interact with the olive paste during the extraction process, the acidity level will increase further. Sealed extraction methods are best to prevent the continued introduction of oxygen, as well as light to the oil.

Lastly, after extraction of the oil is complete, the oil must be stored in cool stainless steel silos that are pumped free of oxygen. This will ensure the quality of the oil; the integrity and stability of the chemical makeup of the oil.

Future prospects
The future of olive extraction points to reducing the negative aspects of the present methods, decreasing the degradation oil produced by the extraction process in itself.

Reducing the oxidation by performing part of the process of malaxation and the extraction under a controlled nitrogen atmosphere
Extracting the nut of the olive before grinding, this will reduce the release of oxidative enzymes present in this organ, and yield a pomace that is free from wood residues, making it possible to be used in animal feeding
Reducing the addition of water to minimize the washing of polyphenols
Improving the sinolea method, through an increase in the efficiency of the adsorption of the oil to the plates, thus reducing the need for the use of standard methods of extraction

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SuperFoods - Extra-virgin Olive Oil

Olive Oil Extraction - Part 4

First cold pressed – cold extraction
Many oils are marketed as first cold pressed or cold extraction, this is a denomination describing the temperature at which the oil was obtained.

In the EU these designations are regulated by article 5 of Regulation 1019 of 2002. This article states that in order to use these designations the olive oil bottler must prove that the temperature of malaxation and extraction was under 27°C (80°F).

For olive oil bottled outside EU countries this regulation does not apply, and thus the consumer has no assurance that these statements are true.

The temperature of malaxation and extraction is crucial due to its effect on olive oil quality. When high temperatures are applied the more volatile aromas are lost and the rate of oil oxidation is increased, producing therefore lower quality oils. In addition, the chemical content of the polyphenols, antioxidants, and vitamins present in the oil is reduced by higher temperatures. The temperature is adjusted basically by controlling the temperature of the water added during these two steps. High temperatures are used to increase the yield of olive oil obtained from the paste.

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Olive Oil Extraction - Part 3

Sinolea
The Sinolea method to extract oil from the olives was introduced in 1972; in this process, rows of metal discs or plates are dipped into the paste; the oil preferentially wets and sticks to the metal and is removed with scrapers in a continuous process. It’s based on the different surface tension of the vegetation water and the oil, these different physical behaviors allow the olive oil to adhere to a steel plaque while the other two phases stay behind.

Sinolea works by continuously introducing several hundreds of steel plaques in to the paste thus extracting the olive oil. This process is not completely efficient leaving a large quantity of oil still in the paste, so the remaining paste has to be processed by the standard modern method (industrial decanter).

Advantages and disadvantages

Advantages
Higher polyphenol content of oil
Low temperature method
Automated
Low labor
Oil/water separation step is not needed
Low energy requirement

Disadvantages
Often must be combined with one of the above methods in order to maximize oil extraction which requires more space and labor.

Large surface areas can lead to rapid oxidation of the olive product

Sale of future machines currently outlawed in the European Union due to difficulty in cleaning large surface areas.

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Seaweed in Olive Oil

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Olive Oil Extraction - Part 2

Modern method: decanter centrifugation
The modern method of olive oil extraction uses an industrial decanter to separate all the phases by centrifugation. In this method the olives are crushed to a fine paste. This can be done by a hammer crusher, disc crusher, depitting machine or knife crusher. This paste is then malaxed for 30 to 40 min in order to allow the small olive droplets to agglomerate. The aromas are created in these two steps through the action of fruit enzymes.

Afterwards the paste is pumped in to an industrial decanter where the phases will be separated. Water is added to facilitate the extraction process with the paste.

The decanter is a large capacity horizontal centrifuge rotating approximately 3000 rpm, the high centrifugal force created allows the phases to be readily separated according to their different densities (solids > vegetation water > oil). Inside the decanter's rotating conical drum there is a coil that rotates a few rpm slower, pushing the solid materials out of the system.

Three, two, and two and a half phases decanters
With the three phases oil decanter, a portion of the oil polyphenols is washed out due to the higher quantity of added water (when compared to the traditional method), producing a larger quantity of vegetation water that needs to be processed.

The two phases oil decanter was created as an attempt to solve these problems. Sacrificing part of its extraction capability, it uses less added water thus reducing the phenol washing. The olive paste is separated into two phases: oil and wet pomace. This type of decanter, instead of having three exits (oil, water and solids), has only two. The water is expelled by the decanter coil together with the pomace, resulting in a wetter pomace that is much harder to process industrially. Many pomace oil extraction facilities refuse to work with these materials because the energy costs of drying the pomace for the hexane oil extraction often make the extraction process sub-economical. In practice, then, the two phases decanter solves the phenol washing problem but increases the residue management problem.

The two and a half phases oil decanter is a compromise between the two previous types of decanters. It separates the olive paste into the standard three phases, but has a smaller need for added water and also a smaller vegetation water output. Therefore the water content of the obtained pomace comes very close to that of the standard three phases decanter, and the vegetation water output is relatively small, minimizing the residue management issues.

Advantages and disadvantages
Advantages

Compact machinery - one decanter can take the place of several presses
Continuous and automated
Limited labor required
highest percent of oil extraction
Vegetable water disposal less of a problem
Olive oil from two-phase centrifugation systems contains more phenols, tocopherols, trans-2-hexenal and total aroma compounds and is more resistant to oxidation than oil from three-phase ones and from hydraulic presses
Disadvantages

Expensive
More technical labor required
High energy consumption
Pomace may end up moist
Greater amount of vegetable water to be disposed of
Reduced antioxidants due to added water
Subject to wear from rocks, grit

Shop The Olive Hut! The Olive Hut features an excellent assortment of olives, olive oils, olive products, nuts, fresh produce, and specialty items.

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Ala Kelly - Italian Olive Oil